Despite their strong positive average returns across numerous asset classes, momentum strategies can experience infrequent and persistent strings of negative returns. These momentum crashes are partly forecastable. They occur in "panic" states - following market declines and when market...

We propose a dynamic heterogeneous agents model which generates testable hypotheses about the formation, timing and bursting of asset price bubbles in the presence of short-sale constraints, given a calibration that is consistent with momentum and reversal effects for unconstrained assets....

Momentum strategies exhibit rare but dramatic losses (crashes), which we show are a result of the leverage dynamics of stocks in the momentum portfolio. When the economy is in a hidden turbulent state associated with a depressed and volatile stock market, the short-side of the momentum portfolio...